Fuse



Feb. 6, 1945. T. B. DOE ET AL 2,368,747

FUSE

Filed Aug. 31, 1940 3 Sheets-Sheet 1 45 48 l8 5 39 42 44 g Q 44 E3 I5 4245 P 4.3

3 6 lo 5 8 7 O 6 3 3 INVENTORS THOMAS E. Dos Rosam- L.KENNG01T ATTORNEYFeb. 6, 1945.. 'r. B. DOE ET AL FUSE Filed Aug. 31, 1940 3 Sheets-Sheet2 48 lllllfl INVENTORS THOMAS B. Doe- ROBERT L. Ksuueorr A TTORNE Y Feb.6, 1945. 2,368,747

FUSE

5 Sheets-Sheet I 5 Filed Aug. 51, 1940 INVENTORS THOMAS 6.005 ROBERT L.KENNGOTT ATTORNEY Patented Feb. 6, 1945 FUSE Thomas B. Doe and Robert L.Kenngott, New

York, N. Y'., assignors to Ford Instrument Company, Inc., Long IslandCity, N. Y., a corporation of New York Application August 31, 1940,Serial No. 354,966

6' Claims.

This invention relates to fuses for projectiles and more particularly tofuses for deto-nating a projectile at a predetermined point initsfiight.

The object of the invention is to provide a fuse for a. projectile whichfunctions upon the projectile being retarded to a velocity correspondingto the predetermined point in its flight.

Another object of the invention is to provide such a fuse in which apredetermined difference between the air pressure onthe nose of the fusedue to its velocity and an air pressure set in a sealed chamber withinthe fuse causes the fuse to function by its action on a member to whichthe firing hammer is permanently secured.

Another object of the invention is to provide such a fuse in whichthefiring caps are held in an inoperative position until after the.projectile has been fired.

Another object of the invention is to provide such a fuse, including anadjustment for calibrating or standardizing the differential pressuresor forces under which the fuse will be actuated.

Other objects of the invention will be apparent from a consideration ofthe specification and drawings in which:

Fig. 1 is a vertical cross-sectional view of an embodiment of theinvention, showing the relation of the parts of the fuse before the fusehas been set to function at a predetermined range;

Fig. 2 is a view similar to Fig. 1, but showing the fuse set to functionat a predetermined range and after the projectile has been fired;

Fig. 3 is a horizontal, cross-sectional view taken on the line 3-3 ofFig. 1;

Fig. 4 is a horizontal, cross-sectional view taken on line 4-4 of Fig.2;

Fig. 5 is a vertical, cross-sectional view, similar to Fig. 1, of amodification of the invention;

and

Fig. 6 is a horizontal, cross-sectional view taken on line 6-6 of Fig.5.

In many of the fuses in use heretofore a powder train leading to thedetonating charge in the projectile is ignited at the time theprojectile is fired and burns to the detonating charge of the projectilein an interval of time depending upon the point of ignition of thepowder train. These fuses not only required that there be placed in thefuse itself a considerable amount of powder, which must be manufacturedwith great care that the rate of propagationof the flame be known andconstant, but their construction has been such that they also requiredthat the powder train be assembled in the fuse at the factory, withattending dangers during assembly, shipment and storage.

To overcome these disadvantages the present" fuse with powder and theinsertion of the firing caps are such simple operations that they may bedone just before securing the fuse to the projectile.

The fuse of the present invention is fired by a firing pin which ismoved to strike the firing cap by the force of air in a chamber, whichis charged to a predetermined pressure, acting on one side of adiaphragm to which the firing pin is attached. Movement of the diaphagmis opposed and prevented until the projectile has reached apredetermined point in its flight-by an air pressure, acting on theother side of the diaphragm, created at the nose of the projectile byits movement through the atmosphere.

It is well known that the pressure on the nose of the projectile'varieswith the velocity of the projectile and the conditions of theatmosphere, and as the velocity of the projectile varies with the timeof flight and the angle of elevation, the nose pressure at anypredetermined range may be calculated for the various sizes ofprojectiles and initial velocities. With these data, which are availablein easily interpretable tables and curves, the pressure to which the airchamber is charged for a selected detonating range is determined. Whenthe projectile has reached the desired range, the nose pressure willhave been reduced to such avalue that it will no longer overcome the airpressure in the chamber and the diaphragm will be moved, causing thefiring pin to strike the firing cap.

In practice it has been found that a difference in pressure of tenpounds on the two sides of the diaphragm was necessary to force or snapthe diaphragm over from one. position to another. Thus, if it is desiredto detonate the projectile at a range having a corresponding nose orvelocity pressure of seventy-five pounds per square inch, the airchamber would be charged to a pressure of eighty-five-pounds per squareinch.

To provide against accidental striking of the firing caps by'the firingpin before the projectile is fired. the fuse is assembled with thediaphragm in its snapped-down position with the firing pin engaging abore in the central portion of the frame or block holding the firingcaps. When the projectile is fired, the nose pressure due to the initialvelocity of the projectile overcomes the pressure of the air in thechamber and snaps the diaphragm to its up position, drawing the firingpin out of engagement with the firing cap frame. This disengagementallows the frame, under the action of centrifugal force due to therotation of the projectile, to move outward in its cavity into aposition such that one of the firing caps is in alignment with thefiring pin. The firing cap is then in a position to be struck by thefiring pin when the diaphragm is snapped down under the force of the airin the chamber, that is, when the nose pressure has decreased to a valuecorresponding to the nose pressure at the point at which it is desiredto detonate the projectile.

It is realized that other fuses have been disclosed whose functioningdepends upon balancing the nose air pressure, due to the movement of theprojectile, against the reaction of springs, air, or centrifugal forcesset up by the masses of certain parts of the fuse. In-these other fusesthe opposing force act on a detent which holds a firing hammer in a,safe position until the desired balance or relation of forces is reachedwhen the detent is moved and the hammer is released. The hammer is thenmoved by centrifugal force or springs to strike the firing cap. In thepresent invention the firing hammer is directly activated by thecontrolling forces, thus adding to the safety, simplicity and positiveaction of the fuse.

Referring to the drawings and particularly to Fig. 1, I represents thebase of the fuse which is adapted to be secured by threads 2 to the noseof the projectile (not shown). In the lower face of base I i bored acylindrical cavity having threaded-walls 3 and a cavity 4, the latterbeing generally rectangular in cross-section but with curved ends. Plugis screwed into the walls 3 by means of a wrench cooperating with holes6. In the central portion of plug 5 is bore 1 in which is placedignition powder 8, which is in communication at its lower end with thedetonating' powder in the projectile (not shown).

Between the upper face of plug 5 and the upper face of cavity 4 slidesframe or block 9, which carries two firing caps l9. Until the projectileis fired, frame 9 is held in its position in the center of cavity 4 byfiring pin II which slides in bore I2 in base I and engages a bore I3 inthe center portion of frame 9. When firing pin I I is moved upward, aswill be hereinafter described, frame 9 is free to move outward under theaction of centrifugal force to one end or the other of cavity 4, whenone of the firing caps ID will be in alignment with the lower end offiring pin I I. Holes I4 in frame 9 are provided as passageways for theflame of the firing cap II] to pass to the powder 8, when frame 9 is inits firing position, as shown in Fig. 2. These passageways may be filledwith powder if desired.

The central portion of the fuse is a core I5 secured to the base I byscrew threads I6. Core I5, among other functions, provides a base andsupport for the inner side walls I! secured to core I5 by screw threadsI8 and the outer side walls I9 which fit into a sloping shoulder 29 oncor IS. The upper ends of the inner side walls I? are closed by nosemember 2I which is hollow and cylindrical in shape. Member 2I is closedat its lower end and has a shoulder 22 in its central portion. Shoulder22 and nut 23, screwed on thread 24, engage the inturned upper ends ofwalls I7 and make an air-tight joint therebetween. Nut 23 has radialslots 25 cut in its lower surface for applying a socket or spannerwrench. The upper ends of the outer walls I9 are secured to member 2I bya nut 26, which engages threads 21, and bears down on the inturned endsof walls I9. The lower surface of nut 26 is cut with a slight slopedownwardly and outwardly. The sloped ends are provided on the outer sidewalls so that the clamping action of the nut 26 will tend to draw thewalls in to make a tight joint which, however, need not be absolutelyair-tight as will hereinafter appear.

In the bore 28 of member 2| slides a cylindrical valve 29 having anaxial bore 30 and a longitudinal slot 3 I. Slot 3| engages pin 32secured in the side walls of member 2I to prevent valve 29 fromturningabout its axis as it slides in bore 28. Threads 33 in the upperportion of bore 39 are provided to fit a tool for removing valve 29 frombore 28, if desired. Ports 34 are cut in the walls of member 2i on alevel between the upper ends of walls I1 and walls I9 and a port 35 iscut in the walls of member 2I below the level of nut 23.

It will thus be seen that an air space 38 is formed between walls I! andI9, which is open at its upper end to the atmosphere through port 34,groove 3I, and bore 28, when valve 29 is in the position shown inFig. 1. Air space 36 is open to the atmosphere through ports 34 and bore28 when valve 29 is in the position shown in Fig. 2. It will also beseen that an air chamber 37 is formed by the inner walls I'I, member 2|,and core I 5, which chamber is open to the atmosphere through port 35,bore 30, and bore 28, when valve 29 is in the position shown in Fig. 1and is closed from bore 39 and the atmosphere when valve 29 is in theposition shown in Fig. 2.

The upper surface of base I is downwardly curved as at 38 and the lowersurface of core I5 is upwardly curved as at 39 to form a cavity 49therebetween. In this cavity is placed a cupshaped diaphragm 4 I. Theupper or open end of diaphragm 4| is secured to core I5 by any suitablemeans such as a ring of solder 42. Diaphragm III is made of any suitablespring metal and is adapted to snap under a differential pressure on itstwo sides from one position to another, such as its down position shownin Fig. 1 and to its up position, shown in Fig. 2. The under side ofdiaphragm 4| is in communication with air space 36 through ports 43 andits upper side is in communication with air chamber 31 through ports 44.

Secured through the center of the diaphragm II is firing pin II, whichextends upwardly through cavity into a bore 45 in the core I5. Apressure head 46 is secured to the upper end of the firing in II by anysuitable means such as riveting, AbOVe'the bore 45 of core I5 i anotherbore 41 of a diameter greater than bore 45.

On the lower shoulder of bore 41 rests a. pressure washer 48 adapted tocontact pressure head 45 when the latter is raised to the position shownin Fig. 2. The pressure washer 48 is forced downwardly by thecompression of spring 49, which compression is adjustable by turning thescrew plug 5EI engaging threads 5| in core I5. The purpose of spring 49and its associated pressure members 48 and 46 is to place an adjustablebias pressure on diaphragm 4| to compensate for any variations in theforce required to snap individual diaphragms from one position toanother, clue to variations in their metal characteristics or slightvariations in their form.

In the modification shown in Figs. 5 and 6, the construction is the sameas that shown in Figs.

1, 2, '3 and 4, except that a different arrangement is provided forplacing the spring bias on the diaphragm M. In the modification shown inFigs. and 6, core I5 is made relatively thin and of such thickness as topermit the upper face of pressure head G6 to extend above the upper faceof core i5 when the diaphragm M is in its up position. Bore i5 is madeof sufficient diameter to accommodate head iii and at the same timeprovide an air passage between chamber 37 and cavity 46.

cover bore and permits air from chamber 3! a to act upon the upper faceof diaphragm M The amount of pressure exerted on head 46 is varied byadjusting the position of screw plug and hence the curvature of spring52 when it is in contact with the upper surface of pressure head 355when the diaphragm 4! is' in its up position.

Assembly and operation In assembling the fuse, diaphragm 4| is securedto core 85 by the ring of solder 42. at a pressure of ten pounds is thenapplied to ports id, with the diaphragm in its up position, as shown inFig. 2. The tension of spring 49 is then adjusted by moving screw plug53 until diaphragm ii snaps over to its down position under 1 thepressure on it upper face of ten pounds plus the force of spring 49.Diaphragm M is left in its down position. The base i is then se cured tothe lower end of core 55.

The nose member 2% is secured to the upper ends of wall H by nut 23clamping the ends of wall I! against the shoulder 22. The inner sidewalls I? are then screwed into the threads IS in the core i5. Outer sidewalls 15 are then placed on shoulder 2!] and the upper ends are securedin position by screwing down On nut 26, which engages the inturned endsof wall I9.

When it is desired to load the fuse, frame 9 with its firing caps ll! isplaced in cavity 4 with the firing pin engaging bore l3. Plug 5, withpowder 8 in place, is then screwed into the bottom of the base i. Thefuse is now ready to be placed on the nose of the projectile.

To set the fuse for the desired .range, valve 29 is inserted in bore 28to the position shown in Fig. 1 and air from a suitable pressure sourceis connected to bore 28. Air chamber 37 i then charged through bore 38and port 35 to the pressure corresponding to the velocity or nosepressure for the desired range plus the calibrated differential pressureof say ten pounds. Air at this pressure also fills cavity 46 throughports M. At the same time air passes through slot 3|, port 36, air space36, and ports 43 to the under side of diaphragm ll. As the diaphragmwill not move except when there is a difference in pressure of tenpounds on its two sides, diaphragm ll will remain in its down position.Upon the completion of the charging of chamber 3?, valve 29 is moveddown to the position shown in Fig. 2, thu sealing port 35. Theprojectile is then ready for firing and is in a safe condition, that is,the firing caps it are held in positions such that they can not bestruck by the firing pin ll.

Air"

- Upon the firing of theprojectile, the nose pres. sure dueto theinitial "velocity of the projectile acting through ports 34, air space35, and ports 45. forces diaphragm N to" its up position, shown in Fig.2. The lower end of the'firing pin II is thus withdrawn from bore [3'and frame 9 is free to move under the action of centrifugal force to itsposition as shown in Fig. 2, with one of the firing caps ID in alignmentwith firing pin I|- The fuse is then in its armed condition.

When the projectile has reached the desired range and the nose pressurehas decreased correspondingly, the pressure in chamber 37 overcomes thenose pressure and the diaphragm snaps to' its down position. Firing pinI! carried by diaphragm M then strikes firing cap ill, thus ignitingpowder 8, which in turn setsv off the detonating charge" of theprojectile.

It is obvious that various changes may be made b those skilled in theart in the details of the embodiment of the invention disclosed in thedrawings and describedv above within the principle and scope of theinvention as expressed in the appended claims.

We claim:

1. In a fuse for projectiles, the combination of a base, a movablemember normally biased in one direction, a cavity in the base, a blockslidable in the cavity and including a central bore and a firing captherein, a firing pin connected to one side of the movable member andadapted to normally en-gage'the bore to position the block in thecavity, an air chamber charged to a predetermined pressure and incommunication with the other side of the movable member, a passageway'for exposing the one side of the movable member to the nose air pressureof the fuse, and spring biasing means for augmenting the effect of thechamber air pressure on the movable member, whereby the firing pin ismoved out of engagement with the bore and is subsequently moved intoengagement with the firing cap in ac, corda nce with the preponderanceof pressures on the sides of the member.

2. In a fuse for projectiles, the combination of a movable member, afiring pin directly controlled by the movement of the member, an airchamber charged to a predetermined pressure and in communication withone side of the movable member, passageways for exposing the other sideof the movable member to the nose air pres sure of the fuse, springbiasing means acting on the said one side of the movable member toaugment the effect of the chamber air pressure on the movable member,and means for adjusting said spring biasing means.

3. In a fuse for projectiles, the combination of a movable memberalternately biased to each of two positions, a firing pin directlyconnected to one side of the movable member, an air chamber charged to apredetermined pressure in excess of atmosphere and formed in part by theother side of the movable member, a second air chamber formed in part bythe one side of the movable member, the fuse having an opening in thenose, a passage connecting the opening to the second air chamber, and aspring acting on the said other side of the movable member to augmentthe effect of the pressure in the first mentioned air chamber on themovable member when the member is biased to a position toward the firstmentioned air chamber, whereby the member is moved to the said positionwhen the effect of the pressure in the second air chamber exceeds theeffect of the pressure in the first mentioned air chamber and the memberis moved to a position toward the second air chamber when the efiect Ihaving a cavity therein, a block in the cavity free to slide and havingon one face a locking recess and a firing cap, the base having an axialbore communicating with the cavity, a flexible diaphragm alternatelybiased to each of two positions supported upon the base, a pin carriedby the diaphragm in the bore of the base and adapted to engage both thelocking recess and the firing cap in difierent positions of the block, asealed pressure chamber formed in part by the face of the diaphragm awayfrom the block charged to a pressure in excess of atmosphere and soconstructed and arranged that the force exerted by the pressure willnormally maintain the pin engaged in the locking recess, and a chamberformed in part by the opposite face of the diaphragm and by the base,and a passage communicating with said last chamber and open to thevelocity air pressure at the nose of the fuse to build up a pressure insaid last chamber due to the velocity of the projectile for opposing thepressure in said first chamber and controlling the actuation of saiddiaphragm.

5. A fuse for projectiles comprising a base have ing a cavity therein, ablock slidable in the cavity and having on one 'face a locking recessand a firing cap, a movable member carried by the base movable betweenfiring and retracted positions, a firing pin mounted on the movablemember and adapted to engage both the recess and the firing cap indifferent positions of the block, spring means urging said movablemember to firing psition a sealed air chamber charged to a predeterminedpressure in excess of atmosphere and formed in part by the face of themovable member away from the cavity and so constructed and arranged thatthe force exerted by the pressure asea'z n' will normally maintain thepin engaged in the locking recess, the fuse having an opening in thenose, a second air chamber formed in part by the face of the movablemember toward the cavity and in part by the base, and a passageconnecting the second air chamber to the opening to build up a pressurein said last chamber due to the velocity of the projectile for opposingthe pressure in said first chamber for controlling the actuation of saidmovable member in accordance with the pressure differentialtherebetween.

6. A fuse for projectiles comprising a base having a cavity therein, ablock slidable in the cavity and having on one face a locking recess anda firing cap, a movable member carried by the base movable betweenfiring and retracted positions, a firing pin mounted on the movablemember and adapted to engage both the recess and the firing cap indifferent positions of the block, spring means urging said movablemember to firing position an air chamber formed in part by the face ofthe movable member away from the cavity and so constructed and arrangedthat the force exerted by the air pressure in said chamber willnormally-maintain the pin engaged in the locking recess, the fuse havingan Opening in the nose, a second air chamber formed in part by the faceof the movable member toward the cavity and in part by the base, apassage connecting the second air chamber to the opening in the nose ofthe fuse to build up a pressure in said last chamber due to the velocityof the projectile for opposing the pressure in said first chamber forcontrolling the actuation of said movable member in accordance with thepressure difierential therebetween, a port connecting the firstmentioned air chamber to the passage for charging, and a valve member insaid passage for 0 controlling the port.

THOMAS B. DOE. ROBERT L. KENNGOTT.

